DOE Study Finds Commercial LED Lamps Fall Short of Claims

[Erik Sine]

Department Of Energy: Study Finds Commercial LED Lamps Fall Short of Claims

December 20, 2006

While compact fluorescent lamps (CFLs) are generally far superior to incandescent lights, many energy professionals expect solid-state lighting sources, such as light-emitting diodes (LEDs), to be the ultimate winner in energy-efficient lighting. Unfortunately, a DOE pilot test of four LED lamps has found that they all fall short of their claims. The pilot tests examined two "downlights"—the type of spotlight that is typically recessed into a ceiling—as well as a task light and an under-cabinet light. The test results, which protect the identity of the LED manufacturers, found that all four lamps fell far short of their claimed output in terms of lumens of light per watt of energy. The manufacturers claimed lighting efficacies of 36 to 55 lumens per watt, while the pilot test found efficacies of 11.6 to 19.3 lumens per watt, placing them below CFLs in lighting efficacy. The study suggests that manufacturers are relying on measurements of how much light an isolated LED produces versus how much the light an LED lamp actually delivers. DOE is continuing its tests to better understand the observed discrepancies. See the test results on the DOE Solid-State Lighting Web site.

Although the efficacy of LED lamps may be in question, the developers of individual LEDs are undoubtedly achieving significant gains in efficacy. For instance, Cree, Inc. announced in October that it has developed a white-light LED that produces up to 85 lumens per watt. DOE helped fund the development of the LED, which can pump out as much as 160 lumens. By 2025, DOE's goal is to achieve 160 lumens per watt in cost-effective, market-ready, solid-state lighting products. See the Cree press release.

Meanwhile, if you're looking for an energy efficient downlight, you might want to consider a CFL. And you're in luck, because DOE's Pacific Northwest National Laboratory (PNNL) has just named 10 winners of its reflector CFL Technology Innovation Competition. The 10 models of CFL downlights demonstrated an average rated life of at least 6,000 hours in elevated temperatures and met DOE's specifications for light output, beam width, and maximum operating temperature. One of the floodlights is even dimmable. See the PNNL Web site.

[B.O.P.]

I've seen this before some time ago but can't remember where.

[YYZ]

Hard to really comment without knowing the products used in the test - though it's worth noting that these seems to be products of a more consumer grade, rather than spec grade architectural. Desk lamps? A19 replacements?

That said - it's more or less accepted that LED are already much more efficient than Halogen and Incandescent and are making gains on CFL and other Fluorescent products. There's some low grade stuff out there (often the offshore stuff) and some good quality stuff as well - which means that you have to look into the company a little and understand what you're buying.

It'll be more interesting and more relevant to our discussions when the DOE does some more sign specific comparisons.

[Erik Sine]

Here's a article I found from The Lighting Research Center, keep in mind it's a couple of years old

spies.pdf

[YYZ]

Interestingly enough - Renssaelar (Lighting Research Center) is using our edgelit system and light engines for some exhibits and displays within their own building.

Those numbers would have changed a great deal since 2004, but as it stands it's still one of the more thorough tests made public. The one done in Sign Business was somewhat thorough but had some messed up criteria. Perhaps we can get our new member (SignTech?) the publisher to be the one to get something done... ?

Edited October 2, 2007 by YYZ